1:2 metal complex dyes, their compositions, their production and their use

ABSTRACT

1:2-metal complex dyes of the formula  
                 
 
     wherein the sympols R 1 , R 1 ′, R 2 , R 2 ′, R 3 , R 3 ′, Y, Z, n, n′, Me, M and (Kat) +  are defined as in the Claims, mixtures thereof, their compositions, their production and their use as anionic dyes for dyeing substrates, especially leather, in brown to red shades.

[0001] In CS 239463 B1 is described a process for the synthesis of metalcomplexes in which an EDTA-metal complex of Cr, Co, Cu or Fe is employedas a reactant for metallization of various azo dye complexants. InExample 5 there is described the synthesis of Saturn Violet LRL bymetallisation of the monoazo compound2-aminophenol-4-suphonamide→phenyl-1-acid with the EDTA-Cu complexproduced by reaction of copper sulphate with tetrasodiumethylenediaminetetra-acetate, and in the “Chemical Abstract” of thisdocument (C.A. 108:114200) there is indicated the symmetrical 1:2chromium complex of this monoazo compound.

[0002] It has now been found that particular monoazo dye metal complexesas defined below have surprisingly good properties as anionic dyestuffs,especially for the dyeing of leather and pelts.

[0003] The invention relates to 1:2 metal complex dyes and mixedcomplexes, their compositions, their production and their use as anionicdyes, especially for dyeing leather.

[0004] The invention thus firstly provides a 1:2-metal complex dye ofthe formula

[0005] wherein

[0006] R₁ signifies H, —NO₂, —SO₃M or —NH(C₁₋₂-alkyl),

[0007] R₂ signifies H, substituted C₁₋₄-alkyl, unsubstituted C₁₋₄-alkyl,—NO₂, —NH, or —OH,

[0008] R₃ signifies H, substituted C₁₋₄-alkyl, unsubstituted C₁₋₄-alkyl,—NO₂, —NH, or —OH,

[0009] R′₁, signifies H, —NO₂, —SO₃M or —NH(C₁₋₂-alkyl),

[0010] R′₂ signifies H, substituted C₁₋₄-alkyl, unsubstitutedC₁₋₄-alkyl, —NO₂, —NH, or —OH,

[0011] R′₃ signifies H, substituted C₁₋₄-alkyl, unsubstitutedC₁₋₄-alkyl, —NO₂, —NH₂ or —OH,

[0012] Y signifies —OM or —NR₄R₅,

[0013] Z signifies —OM or —NR₄′R₅′,

[0014] R₄ signifies H, C₁₋₄-alkyl, a substituted aromatic ring or anunsubstituted aromatic ring,

[0015] R₄′ signifies H, C₁₋₄-alkyl, a substituted aromatic ring or anunsubstituted aromatic ring,

[0016] R₅ signifies H, C₁₋₄-alkyl, a substituted aromatic ring or anunsubstituted aromatic ring,

[0017] R₅′ signifies H, C₁₋₄-alkyl, a substituted aromatic ring or anunsubstituted aromatic ring,

[0018] n signifies 0 or 1,

[0019] n′ signifies 0 or 1,

[0020] M signifies hydrogen or a cation,

[0021] (Kat)⁺ signifies a counter-ion

[0022] and Me signifies a complex-forming metal,

[0023] with the proviso that if Y and Z signify both —NH₂, Me does notsignify Cr,

[0024] and mixtures of two or more thereof.

[0025] The compounds of the invention may be produced by syntheticprocesses analogous to known processes, i.e. by diazotization, couplingand metallization reactions and optionally other modification reactionsas required.

[0026] More particularly, the process for the production of the 1:2metal complexes of the invention is characterized in that at least onemonoazocompound of formula

[0027] and at least one monoazo-compound of formula

[0028] in which, when n or n′ is 1, the carboxy group may optionally bein salt form, are metallized with at least one 1:2-complex-forming metalcompound.

[0029] The compounds of formula (II) are known or may be produced byknown methods conventional per se, by coupling the diazocompound of anamine of formula

[0030] to a coupling component of formula

[0031] Analogously the compounds of formula (III) are known or may beproduced by known methods conventional per se, by coupling thediazocompound of an amine of formula

[0032] to a coupling component of formula

[0033] Diazotization of amines of formulae (IV) and (VI) may be carriedout under conventional conditions, in particular with a nitrite(preferably sodium nitrite) in acidic aqueous medium (preferably in thepresence of hydrochloric acid) and at low temperatures, e.g. in therange of −5° C. to +10° C., preferably 0° to 5° C.

[0034] The coupling reactions of the diazonium compounds to therespective coupling components may also be carried out in a mannerconventional per se, advantageously at temperatures in the range of −5°C. to +30° C., preferably below 25° C. The coupling of the diazocompounds to the compounds of formulae (V) or respectively (VII) may becarried out under distinctly basic pH conditions, preferably at a pH inthe range of 8 to 11.5, preferably 9.5 to 11.5.

[0035] The reactions may be carried out in aqueous medium or also inaqueous/organic medium, the organic medium being preferably awater-miscible inert solvent (e.g. an alcohol or dioxane), preferably inonly aqueous medium.

[0036] The compounds of formulae (V) and (VII) are known or may besynthetised by known methods by arylation of γ-acid or J-acid.

[0037] Where in the significance of any of R₂, R₃, R₂′ or R₃′ an alkylradical is substituted, the substituents may be selected from knownsubstituents conventional in the art of azo dyes, e.g. from —OH,C₁₋₂-alkoxy, —NH₂, —CN, —COOM₁ and —SO₃M. M₁ signifies hydrogen or hasone of the significances of M. Preferably any alkyl radical in thesignificance of any of R₂, R₃, R₂′ or R₃′ is unsubstituted.

[0038] The C₃₋₄-alkyl radicals may be linear or branched. Among theC₁₋₄-alkyl radicals the lower molecular ones are preferred, inparticular ethyl and especially methyl.

[0039] If R₄, R₄′, R₅ or R₅′ signifies an unsubstituted or substitutedaromatic ring, this ring preferably is a benzene ring and thesubstituents may be selected from known substituents conventional in theart of azo dyes, e.g. from C₁₋₂-alkyl, —OH, C₁₋₂-alkoxy, —NH₂, —CN,—COOM₁ and —SO₃M; preferably such optionally substituted aromaticradical is a radical of formula

[0040] wherein

[0041] R′ signifies hydrogen, C₁₋₂-alkyl, —OH, C₁₋₂-alkoxy, —NH₂, —CN,—COOM₁ or —SO₃M and R″ signifies hydrogen or C₁₋₂-alkyl.

[0042] R″ preferably signifies hydrogen.

[0043] R′ preferably signifies hydrogen or —COOM₁.

[0044] R₁ preferably is in ortho-position with reference to—(CO)_(n)—O—. Preferably R₁ signifies hydrogen or —NO₂, more preferablyhydrogen.

[0045] R₁′ preferably is in ortho-position with reference to—(CO)_(n)—O—. Preferably R₁′ signifies hydrogen or —NO₂, more preferablyhydrogen.

[0046] R₂ and R₃ may be in any of the available positions of the phenylring, R₃ preferably is in para-position with reference to the —NH—bridge linked to the naphthalene radical, and R₂ is in any of the otheravailable positions. Preferably at most one of R₂ and R₃ signifies —OHor —NH₂. Preferably R₃ signifies hydrogen, —NH₂, —OH or —NO₂, morepreferably hydrogen or —NO₂, R₂ most preferably signifies hydrogen.

[0047] R₂′ and R₃′ may be in any of the available positions of thephenyl ring, R₃′ preferably is in para-position with reference to the—NH— bridge linked to the naphthalene radical, and R₂′ is in any of theother available positions. Preferably at most one of R₂′ and R₃′signifies —OH or —NH₂. Preferably R₃′ signifies hydrogen, —NH₂, —OH or—NO₂, more preferably hydrogen or —NO₂. R₂′ most preferably signifieshydrogen.

[0048] R₄ and R₅ may have equal or different significances. R₄preferably signifies hydrogen, C₁₋₂-alkyl or a radical of formula (α).R₅ preferably signifies hydrogen or C₁₋₂-alkyl, more preferablyhydrogen.

[0049] R₄′ and R₅′ may have equal or different significances. R₄′preferably signifies hydrogen, C₁₋₂-alkyl or a radical of formula (α).R₅′ preferably signifies hydrogen or C₁₋₂-alkyl, more preferablyhydrogen.

[0050] Preferably Y and Z do not signify both OM or both NH₂.

[0051] Y preferably signifies —OM or —NHR₄″, and R₄″ signifies hydrogen,methyl or a radical of formula

[0052] in which R′″ signifiies hydrogen or —COOM₁.

[0053] Z preferably signifies —NHR₄, more preferably —NHR₄″, in whichR₄″ is as defined above and, if the molecule contains two groups offormula —NHR₄″, the two R₄″ may have equal or different significances.Preferably, if Y and Z signify both a group —NHR₄″, at most one of thetwo R₄″ signifies a radical of formula (α) or (α′); more preferably oneof the two R₄″ signifies hydrogen and the other signifies C₁₋₄-alkyl ora radical of formula (α), most preferably methyl or a radical of formula(α′). Particularly preferably Y signifies —OM or —NH₂ and Z signifies agroup —NHR₄″, in which, if Y signifies —NH₂, R₄″ in Z does not signifyhydrogen.

[0054] Where M signifies a cation this may be any cation conventionalper se in anionic metal complex dyes, conveniently a non-chromophoriccation, in particular an alkali metal cation (especially lithium, sodiumor/and potassium) or an ammonium cation (e.g. unsubstituted ammonium orammonium mono-, di- or tri-substituted with C₁₋₂-alkyl or/andC₂₋₃-hydroxyalkyl), alkali metal cations being preferred. The metalcomplex dyes of the invention may advantageously also be in partial saltform, i.e. where some of the M are salt-forming cations and some arehydrogen (or hydronium). (Kat)′ may be any cation as is formed in thesynthesis of the metal complex dye, e.g. as indicated above for M, anddepends thus also on Me and further also on the complex forming reactionconditions (namely the pH and the employed solvent), or a cationintroduced by ion exchange; in the free acid form it is indicated as ahydronium ion. Similarly, M₁ may be hydrogen or any cation as is formedin the synthesis of the metal complex dye, depending also on the complexforming reaction conditions (namely the pH and the employed solvent), ora cation introduced by ion exchange, analogously as indicated above forM.

[0055] The radicals of formulae

[0056] may be linked to the 6- or 7-position of the respectivenaphthalene nucleus, of which position 6 is preferred.

[0057] The 1:2 complex-forming metal Me may be any suitable metal, i.e.any metal suitable for 1:2 metal complex formation, in particularchromium, cobalt, iron, manganese, titanium, zirconium (also zirconyl)or/and aluminium, of which are preferred chromium, cobalt and iron,especially cobalt and/or iron.

[0058] Preferred 1:2 metal complexes of the invention are those offormula

[0059] in which

[0060] Y₁ signifies —OM or —NHR₄,

[0061] R₁″ signifies hydrogen or —NO₂,

[0062] R₁″ signifies hydrogen or —NO₂

[0063] and R₄′″ has independently from R₄ one of the significances ofR₄, provided that, if Y₁ signifies —NH₂, R₄′″ does not signify hydrogen,and that if Y₁ signifies —NHR₄, at most one of R₄′″ and R₄ signifies aradical of formula (α),

[0064] especially those of formula

[0065] in which

[0066] Me′ signifies Cr, Co or Fe,

[0067] Y₂ signifies —OM or —NHR₄″

[0068] and R₄″″ has independently from R₄″ one of the significances ofR₄″, provided that, if Y₂ signifies —NH₂, R₄″″ does not signifyhydrogen, and that if Y₂ signifies —NHR₄″, at most one of R₄″″ and R₄″signifies a radical of formula (α′).

[0069] The metal complexes of formula (I) may be synthetized bymetallizing the respective compounds of formulae (II) and (III). Themetallization to the metal complexes may be carried out in analogy toknown metal complex formation reactions.

[0070] For the metallization of the compounds of formulae (II) and (III)there may be employed conventional suitable complex-forming metalcompounds, in particular salts, e.g. acetates or hydrosoluble salts ofmineral acids, in particular chromium trichloride, cobalt dichloride,iron di- or trichloride, chromium trifluoride, manganese chloride,acetate or sulphate, aluminium chloride, titanium chloride, zirconiumtetrachloride or sulphate, zirconyl chloride, cobalt sulphate ornitrate, iron-II- or -III-sulphate, chromium sulphate, chromium orcobalt acetate, potassium chromium sulphate, ammonium chromium sulphate(e.g. chrome alums) and optionally, with the addition of a reducingagent e.g. of glucose, also sodium or potassium chromate or bichromate.

[0071] Chromation may be carried out directly up to the 1:2 chromiumcomplex stage or—especially for the production of asymmetrical 1:2 Crcomplexes—by degrees over the 1:1 chromium complex stage and thenfurther complexation up to the 1:2 chromium complex stage.

[0072] Chromation may be carried out in aqueous medium, preferably at pHvalues in the range of 2 to 10 and temperatures in the range of 95 to130° C., if necessary under superatmospheric pressure. Optionally thereaction may be carried out with addition of organic solvents or alsoonly in organic solvents. Suitable organic solvents are preferably thosethat are miscible with water, have a boiling point above 100° C. and inwhich the azo dyes and the metal salts are soluble, e.g. glycols, etheralcohols or amides (e.g. ethylene glycol, polyethylene glycol,β-ethoxyethanol, β-methoxy-ethanol, formamide or dimethylformamide). Forthe production of asymmetrical 1:2 chromium complex compounds thechromation may be carried out gradually, synthetizing first the 1:1chromium complex of one of the complexants and then synthetizing fromthis with a second complexant the 1:2 complex. The 1:1 cbromiumcomplexes may be produced in conventional manner, e.g. under analogousconditions as for the 1:2 chromium complexes, but preferably understronger acidic pH-values, advantageously at pH<3. It is however also ofadvantage to synthesize 1:2 chromium mixed complexes, e.g. bysimultaneously metallizing complexants of formulae (II) and (III)different from each other.

[0073] The metallization of azocompounds of formulae (II) and (III) tothe respective iron-complexes, i.e. 1:2 iron complexes, may be carriedout in conventional manner, suitably in aqueous medium, advantageouslyat pH-values in the range of 3.5 to 7, preferably 4.5 to 6, withheating. Preferably the metallization to iron complexes is carried outat temperatures in the range of 40° C. to reflux temperature, preferably50° to 100° C.

[0074] The metallization of azocompounds of formulae (II) and (III) tothe corresponding 1:2-cobalt complexes, may be carried out inconventional manner, suitably in aqueous medium, advantageously atpH-values in the range of 8 to 12, preferably 10 to 11, optionally withheating. Preferably the metallization to cobalt complexes is carried outat temperatures in the range of 40° C. to 90° C., preferably 50° to 70°C.

[0075] Where a metal compound of a metal cation in bivalent form Me²⁺ isused for complex formation, an oxidising agent, e.g. H₂O₂, may be addedin order to optimise the yield of complex formation of the metal withdegree of oxidation=3 (=Me³⁺).

[0076] Other metallizations may be carried out in analogous way, asconventional per se.

[0077] Preference is given to 1:2 metal complexes of asymmetricalconstitution, i.e. of formula (I) in which the radicals of thecomplexants of formulae (II) and (III) are different from each other,i.e. in which the position or/and the significance of R₁ is differentfrom the one of R₁′ and/or the position or/and the significance of R₂ isdifferent from the one of R₂′ and/or the position or/and thesignificance of R₃ is different from the one of R₃′ and/or thesignificance of n is different from the one of n′ and/or the position ofthe radical of formula (β) is different from the one of the radical offormula (β′).

[0078] According to a preferred feature of the invention the radicals offormulae (β) and (β′) and their positions are equal, while the radicalsof the diazo components—i.e. of those of formulae (IV) and (VI)—aredifferent, preferably by Y being different from Z, while R₁ may have thesame significance and position as R₁′ and also n may be =n′.

[0079] Preferred complexes of formula (I′) are those in which R₁″ andR₁′″ signify hydrogen and Y₁ signifies —OM or —NH₂, and preferredcomplexes of formula (I″) are those in which Y₂ signifies —OM or —NH₂.

[0080] According to a further preferred feature of the invention thereare produced mixed 1:2 metal complexes by metallising a mixture of twoor more different monoazocompounds of formulae (II) and (III), so thatthere are formed statistical mixtures of the corresponding asymmetrical1:2 metal complex of formula (I) with the respective symmetrical 1:2metal complex of a dye of formula (II) and the one of a dye of formula(III). In such mixtures of asymmetrical and symmetrical complexes theproportion of asymmetrical complex present may vary depending on themetallisation reaction conditions, e.g. in the range of 20 to 80 mol-%of the total metal complex mixture, usually 30 to 75 mol-%, mostly 40 to70 mol-%.

[0081] According to a still further preferred feature of the inventionthere are produced mixed-metal complexes by metallising the respectivemonoazocompounds of formulae (II) and (III) with two or more differentcomplex-forming metals, so that there are formed correspondingstatistical mixtures of the 1:2 metal complexes of formula (I) in whichMe has two or more different significances. This may be accomplishedeither by using mixtures of two or more different complex forming metalcompounds or preferably by consecutive stepwise metallization with twoor more different complex forming metal compounds, i.e. complex formingcompounds of two or more complex forming metals Me, and at the samereaction conditions as used for the individual metal complex formationas described above.

[0082] The equivalents ratio of complex forming metal compounds referredto complex forming metal in the production of these mixed-metalcomplexes may vary broadly, i.e. <100% of the stoichiometric orcalculated quantity required for full 1:2 metallization, e.g. from 2 to98%, or even 40 to 95%—e.g. 50%-, of a metal Me₁, and the remainder,e.g. 2 to 98%, or even 60 to 5%—e.g. 50%-, of one or more other metals,in particular of a metal Me₂. For this purpose Me₁ preferably ischromium or cobalt and Me₂ preferably is aluminium or iron, or, if Me₁is chromium, Me₂ may also be cobalt, or conversely, if Me, is cobalt,Me₂ may also be chromium. Most preferably Me₁ is cobalt and Me₂ is ironor chromium. One equivalent of complex forming metal compound referredto complex forming metal Me is one mole of complex forming metalcompound divided by the number of metal atoms Me present in ionic formin the complex forming metal compound. The calculated quantity ofcomplex forming metal compound required for full 1:2 metallization mayvary slightly from the stoichiometric one, by including a certainproportion that may be involved in an accompanying non-complex-formingside reaction, and may vary depending on the kind of involved productsand on the reaction conditions. The required calculated quantity maythus e.g. be in excess of about 0.5 to 15% mostly 1 to 12% over thestoichiometric one.

[0083] For example, if a metal complex mixture of 50 mol-% 1:2 Cocomplex and 50 mol-% Fe complex is desired, first 50% of thestoichiometric or calculated amount of cobalt (i.e. 50% of the amount ofcobalt required for full 1:2-cobalt complex formation) as cobaltsulphate is added at a pH in the range of 8.0 to 12.0 and at atemperature in the range of 40 to 90° C. After 1 hour stirring, the pHis lowered with hydrochloric acid up to 4.0 to 7.0 and 50% of thestoichiometric or calculated amount of iron (i.e. 50% of the amount ofiron required for full 1:2-iron complex formation) as iron chloride isadded and the reaction mixture is stirred during 1 hour at a pH in therange of 4.0 to 7.0 and a temperature in the range of 50 to 90° C.

[0084] Upon completion of the required coupling and metallizationreactions the obtained dyes or mixtures thereof may be isolated from themother-liquor in a manner conventional per se, e.g. by salting-out or byacidification with a strong mineral acid or e.g. by evaporation, upondialysis with a suitable membrane. If desired, the dye may, uponisolation or dialysis, be blended with suitable blending agentsconventional per se, e.g. with alkali metal salts (sodium carbonate,sodium sulphate or sodium chloride), with non-electrolyte blendingagents (mainly urea or/and oligosaccharides, e.g. dextrin) or/and withanionic surfactants, in particular hydrocarbon sulphonates or otherorganic sulphonates, e.g. sulphonated castor oil, sulphosuccinates orlignin sulphonate. If a surfactant is employed, the weight ratio of thesurfactant to the dye is advantageously in the range of 5:95 to 40:60.If desired, especially if the composition contains an anionicsurfactant, as indicated above, it may be formulated with water asconcentrated liquid dye compositions, preferably with a dry-substancecontent in the range of 10 to 70%, more preferably 20 to 50% by weight,referred to the weight of the composition.

[0085] The 1:2 metal complex dyes of the invention distinguish by theirsolubility and stability properties even in aqueous solution. They serveas anionic dyes and are suitable for dyeing substrates that are dyeablewith anionic dyes.

[0086] Any substrate that is dyeable with anionic dyes is suitable as asubstrate that may be dyed with the metal complexes of the invention,these include natural and regenerated cellulose, polyurethanes,basically modified high polymers (e.g. basically modifiedpolypropylene), natural or synthetic polyamides or anodised aluminium,in particular, however, leather substrates. The substrate to be dyed maybe in any conventional form, e.g. in the form of loose fibres,filaments, yarns, woven or knitted goods, non-woven webs, carpets,half-ready-made and ready-made soft goods and tanned leather or pelts.The dyes may be employed in any desired concentration up to thesaturation of the substrate. The dyeing may be carried out by anyconventional method that is suitable for the substrate to be dyed, e.g.by exhaustion or impregnation methods (e.g. padding or printing),preferably from aqueous medium; for synthetic substrates, the dye mayoptionally also be incorporated into the synthetic mass. Paper may bedyed in the pulp or after sheet formation.

[0087] The dyes of the invention are, however, mainly suitable for thedyeing of leather and pelts.

[0088] Any kinds of leather which are conventionally dyed from aqueousmedium are suitable, particularly grain leather (e.g. nappa from sheep,goat or cow, and box-leather from calf or cow) suede leather (e.g.velours from sheep, goat or calf and hunting leather), split velours(e.g. from cow or calf skin), buckskin and nubuk leather; further alsowoolled skins and furs (e.g. woolled suede leather). The leather mayhave been tanned by any conventional tanning method, in particularvegetable, mineral synthetic or combined tanned (e.g. chrome tanned,zirconyl tanned, aluminium tanned or semi-chrome tanned). If desired,the leather may also be re-tanned; for re-tanning there may be used anytanning agent conventionally employed for re-tanning, e.g. mineral,vegetable or synthetic tanning agents [e.g. chromium, zirconyl oraluminium derivatives, oak, quebracho, chestnut or mimosa extracts,aromatic syntans, polyurethanes (co)-polymers of (meth)acrylic acidcompounds or melamine/, dicyanodiamide/and/or urea/-formaldehyderesins].

[0089] The leathers may be of various thicknesses, thus, there may beused very thin leathers, such as book-binder's leather or glove-leather(nappa), leather of medium thickness, such as shoe upper leather,garment leather and leather for handbags or also thick leathers, such asshoe-sole leather, furniture leather, leather for suitcases, for beltsand for sport articles; woolled leathers and furs may also be used.After tanning (in particular after a retanning) and before dyeing, thepH of the leather is advantageously set to values in the range of4.0-8.0 (the leather is “neutralised”); depending on the kind of theleather, there may be chosen an optimum pH range, e.g. for grain leatherpH values in the range of 4.0-6.0, for suede leather and split veloursand for very thin leathers pH-values in the range of 4.5 to 8.0 and forintermediately dried suede leathers and intermediately dried splitvelours, the pH may range in the range of 5.0-8.0. For the adjustment ofthe pH-value of the leather there may be employed conventionalassistants; for tanned leather of acidic character the pH may beadjusted by addition of suitable bases, e.g. ammonia, ammoniumbicarbonate or alkali metal salts of weak acids, e.g. sodium formate,sodium acetate, sodium bicarbonate, sodium carbonate or sodiumbisulphite, of which sodium formate and ammonia are preferred. Sodiumcarbonate and sodium bicarbonate are usable in particular as secondbases for the exact adjustment of the superficial pH-value of theleather. Mineral tanned leather may, if desired, also be masked, e.g.with alkali metal formate, oxalate or polyphosphate or e.g. withtitanium/potassium oxalate.

[0090] The dyeing may be carried out in a manner known per se, suitablyin an aqueous medium and under conventional temperature and pHconditions, e.g. in the temperature range of 20° C.-80° C., preferably25° C.-70° C., milder temperature conditions, in particular in the rangeof 25° C.-40° C., being preferred for the achievement of deeperpenetrations and for the dyeing of woolled skins and furs. The pH-valuesof the dye-bath may, in general, range broadly; mainly from pH 9 to pH3; in general the dyeing may be advantageously begun at higher pH-valuesand concluded at lower pH-values. Preferably the dyeing is carried outat pH-values ≦4, in particular in the range of 9 to 4 and for theconclusion of the dyeing procedure the pH-value is lowered (e.g. byaddition of an acid conventional in the leather dyeing technique such asacetic acid or formic acid) preferably to values in the range between 4and 3. The dye concentration may range broadly, if desired, up to thesaturation degree of the substrate, e.g. up to 5%, referred to the wetweight of the substrate.

[0091] The dyeing may be carried out in one or more stages, e.g. in twostages, optionally with insertion of charge reversal of the substrate bymeans of conventional cationic assistants. If desired, the dyeing may becarried out in the presence of a dyeing assistant; these are mainlyconventional non-ionic or anionic products (in particular hydrophilicsurfactants, preferably hydrophilic polysaccharide derivatives,polyoxyethylated alkyl phenols, ligno-sulphonates or sulpho-groupcontaining aromatic compounds). Since the dyes of the inventiondistinguish by their surprisingly good fastness to acids, neither thedyeing procedure nor the dyeing are impaired by any required acidaddition during the dyeing or also afterwards (the obtained dyeings aree.g. also suitable as substrates for after-treatments and finishingsunder acidic conditions).

[0092] A fatting may, if desired, be carried out before and/or after thedyeing process, in particular also in the same liquor. For fatting afterthe dyeing process the fatting agent is advantageously added before thepH of the liquor is lowered, preferably to values between 3 and 4.

[0093] For the fatting (in particular fat-liquoring) step there may beused any conventional natural animal, vegetable or mineral fat, fat oil,wax, resin or resin-oil or chemically modified animal or vegetable fator oil, which include in particular tallow, fish oils, neats-foot oil,olive oil, castor oil, rapeseed oil, linseed oil, wood oil, cottonseedoil, sesame oil, corn oil and Japanese tallow and chemically modifiedproducts thereof (e.g. hydrolysis, transesterification, oxidation,hydrogenation or sulphonation products), bees-wax, Chinese wax, carnaubawax, montan wax, wool fat, colophony, birch oil, shellack, mineral oilswith boiling range within 300° C. and 370° C. (particularly theso-called “heavy alkylates”), soft paraffin, medium paraffin, hardparaffin, vaseline, ceresin and methyl esters of C₁₄₋₂₂-fatty acids; andsynthetic leather fatting agents, including esters, in particular estersof polybasic acids (e.g. phosphoric acid) with optionally oxyethylatedfatty alcohols. Of the above the mentioned methyl esters, sulphonationproducts and phosphoric acid partial esters are particularly preferred.By the term “sulphonation” for the fatting agents, there is meantgenerally the introduction of a sulpho group including also theformation of a sulphato group (=“sulphating”) and the introduction of asulpho group by reaction with a sulphite or SO₂ (=“sulphiting”).

[0094] A conventional leather softener, in particular a cationic leathersoftener may, if desired, be applied in a final step, particularly iffatting has been carried out with a sulphonated fat-liquoring agent.

[0095] The treated substrate may then be further treated in conventionalmanner, e.g. rinsed or washed, drained, dried and cured.

[0096] A further embodiment of the present invention is a substrate dyedby a process using compounds of formula (I) or mixtures thereof.

[0097] The 1:2-metal complex dyes of the invention are, especially inthe form of their alkali metal salts, readily soluble in water; theydisplay surprisingly good fastness to acids and are distinguishedespecially on leather by their good build-up, good penetration dyeingsof the leathers being also obtainable. The dyeings particularly onleather, have excellent fastness properties, for example wet-fastnesses,fastness to rubbing and to dry cleaning and above all fastness to acids,light-fastness and stability to PVC-migration are to be pointed out.There may be obtained very level, intense, fine dyeings in brown to redshades, in particular reddish brown to brownish red, especially alsobordeaux dyeings, grain side and velours side being very evenly dyed.The dye exhaustion of the dye bath is also satisfactory. The 1:2 metalcomplex dyes of the invention may also be employed in admixture withother dyes of different shade and similar coloristic behavior, mainly1:2 metal complexes of mono- or/and disazodyes, e.g. those described inU.S. Pat. No. 5,602,237, U.S. Pat. No. 5,008,379 and/or DE-A-4407802, togive dye mixtures and dyeings of corresponding combined shades. Inadmixture with such dyes with which the dyes of the invention arecombinable, there may also be obtained very intense and regular dyeingsof high yield and optimum fastnesses.

[0098] In the following examples parts and percentages are, if nototherwise stated, by weight; the temperatures are indicated in degreesCelsius and parts by volume relate to parts by weight as ml to g. Whereit is stated that a compound is diazotised in a conventional way, thereare meant diazotisation reaction conditions as described above (i.e.with sodium nitrite in aqueous acidic medium in the presence ofhydrochloric acid, at 0-5° C.). The reactants employed in the syntheticexamples and the components employed in the Application Examples, otherthan the dyes of the invention, are commercially available products.

EXAMPLE 1

[0099] 18.8 parts of 1-hydroxy-2-amino-4-benzenesulphonic acid and 20.1parts of 1-hydroxy-2-amino-4-benzenemethylsulfonamide are diazotized ina conventional way and coupled to 73 parts of phenyl-J-acid dissolved in500 parts of water at pH 10.0-11.0 (set with NaOH). Once the coupling iscomplete, the solution is heated to 60° C. and 28 parts of cobaltsulphate heptahydrate is added, keeping the pH>10.0 with the addition of20 parts of sodium hydroxide 25% solution. The reaction mixture is heldat this temperature with stirring until the cobaltation reaction iscompleted. Finally the Co-complex dye is salted out, suction filteredand dried. There are obtained 200 parts of a powder that dyes leather ina bordeaux shade. The dye is a mixture of symmetric and asymmetriccobalt complexes, in which the asymmetric complex preponderates andcorresponds in the form of the free acid to the formula:

[0100] and the symmetric ones correspond in the form of the free acidsto the formulae

[0101] and is obtained as sodium salt.

EXAMPLE 2

[0102] The procedure described in Example 1 is repeated, but instead ofusing 28 parts of cobalt sulphate heptahydrate, only 14 parts thereofare used. After 1 hour of cobaltation, the pH is adjusted to 6.5 to 7.0with 20 parts of hydrochloric acid, 15 parts of iron trichioridehexahydrate are added, keeping the pH at 4.5-5.0, if necessary by theaddition of aqueous 25% NaOH solution, and the reaction mass is stirredone hour. Finally, the dye is salted out, suction filtered and dried.There is obtained 200 parts Of a dark powder that dyes leather in a redbrown shade. The dye is a mixture of asymmnetric and symmetric cobaltcomplexes, which in the form of the free acids correspond to theformulae shown in Example 1, and of asymmetric and symmetric ironcomplexes, which in the form of the free acids correspond to theformulae

[0103] and is obtained as sodium salt.

[0104] The following table contains the above Examples 1 and 2 andfurther dyes (Examples 3-20) of the invention which are producedanalogously to the methods described in Examples 1 and 2 and correspondin the form of the free acids to the formula

[0105] Chromation in Examples 3, 4, 8, 16 and 19 is carried out withchrome alum (potassium/chromium sulphate) at pH 5.0-5.5 at 95-100° C.

[0106] In the last column of the table there is indicated the shade ofthe dyeing on leather. Ex. Nr. Y Z n = n′ Me and molar ratio pos. R₃ =R₃′ Shade on leather 1 —OH. —NHCH₃ 0 Co 6 H bordeaux 2 —OH. —NHCH₃ 0Co/Fe 50/50 6 H reddish brown 3 —OH. —NHCH₃ 0 Cr 6 H bordeaux 4 —OH.—NHCH₃ 0 Co/Cr 50/50 6 H red brown 5 —OH. —NH₂ 0 Co 6 H bordeaux 6 —OH.—NH₂ 0 Fe 6 H brown 7 —OH. —NH₂ 0 Co/Fe 50/50 6 H red brown 8 —OH. —NH₂0 Co/Cr 50/50 6 H red brown 9 —OH. —NH₂ 0 Co 7 H bordeaux 10 —OH. —NH₂ 0Co 6 —NO₂ bordeaux 11 —NH₂ —NHCH₃ 0 Co 6 H bordeaux 12 —NH₂ —NHCH₃ 0 Fe6 H brown 13 —OH

0 Co 6 H bordeaux 14 —OH

0 Co 6 H bordeaux 15 —OH —NH₂ 0 Co/Fe 95/5 6 H bordeaux 16 —OH —NH₂ 0 Cr6 H brown 17 —OH —NH₂ 1 Co 6 H brown 18 —OH —NH₂ 1 Co 6 —NO₂ brown 19—OH —NH₂ 1 Cr 6 H brown 20 —OH —NH₂ 1 Co 6 —NO₂ brown

EXAMPLE 21

[0107] The procedure described in Example 1 is repeated, with thedifference that instead of 18.8 parts of1-hydroxy-2-amino-4-benzenesulphonic acid and 20.1 parts of1-hydroxy-2-amino-4-benzene-methylsulfonamide there are employedequivalent amounts of 1-hydroxy-2-amino-6-nitro-4-benzenesulphonic acidand of 1-hydroxy-2-amino-6-nitro-4-benzenemethylsulfonamide. Theobtained dye is a mixture of symmetric and asymmetric cobalt complexes,in which the asymmetric complex preponderates and corresponds in theform of the free acid to the formula:

[0108] and the symmetric ones correspond in the form of the free acidsto the formulae

[0109] and is obtained as sodium salt. It dyes leather in bordeauxshades.

[0110] In the above Examples, the pH being set with NaOH and the dyesbeing salted out with sodium chloride, the dyes are obtained in sodiumsalt form. By salting out with KCl corresponding mixed Na/K-salts areobtained. By using corresponding bases for setting the pH (i.e. KOH orLiOH) and the respective salt for salting out the dyes are obtained inthe corresponding K and Li salt forms. By precipitation of the dye byacid addition and neutralising with triethanolamine or ammonia, thecorresponding amine or ammonium salt forms are obtained.

APPLICATION EXAMPLE A

[0111] 100 parts of a wet blue bovine box side leather are neutralizedin a dyeing drum with 250 parts of water and 0.8 parts of sodiumbicarbonate at 35° C. during 45 minutes. The leather is then washed with1000 parts of water at 25° C. After 5 minutes the leather is dyed at 50°C. with 250 parts of water and 0.8 parts of the metal complex dyeproduced according to Example 1, previously dissolved in 80 parts ofwater of 50° C. After 20 minutes 4 parts of an 80% emulsion of asulphited fish oil are added for fatting and fatting is continued for 45minutes. Then the bath is acidified with 0.5 parts of an 85% formic acidsolution and drumming is continued for 20 minutes. Finally the liquor isdrained off and the leather is rinsed at 25° C. with 1000 parts ofwater. The leather is drained, dried and cured in conventional way. Aleather dyed with a level pastel bordeaux shade with outstandingfastnesses (in particular wet fastnesses, fastness to dry cleaning,fastness to acids, light fastness and PVC migration resistance) isobtained.

APPLICATION EXAMPLE B

[0112] 100 parts of an intermediately dried chrome-tanned suede splitleather are wetted back with 800 parts of water at 50° C., 2 parts of25% ammonia solution and 0.5 parts of the adduct of 10 moles of ethyleneoxide to 1 mol of nonylphenol for 90 minutes; the bath is then drainedoff and 600 parts of water at 50° C., 1 part of a 25% ammonia solutionand 1 part of a fat-liquoring agent (an emulsion of fatty acid esters)are added. After 10 minutes, 4 parts of the metal complex dye producedaccording to Example 1, previously dissolved in 400 parts of water of50° C., are added for pre-dyeing. After 60 minutes, 2 parts of an 85%fomic acid are added and drumming is continued for 20 minutes. 2 partsof a 20% solution of the product obtained by quaternization withdimethylsulphate of the benzylation product of diethylenetriamine arethen added and after 20 minutes 2 parts of the same dyestuff as used forpre-dyeing, previously dissolved in 200 parts of water of 50° C., areadded. Drumming is continued for 40 minutes, then the bath is acidifiedwith two additions of 1.5 parts of an 85% formic acid solution at aninterval of 10 minutes between the two additions. After 10 minutes thebath is drained off and the leather is rinsed, drained, dried and curedas usual. There is obtained a leather dyed in a level bordeaux shadewith outstanding fastnesses (in particular wet fastnesses, fastness todry cleaning, fastness to acids, light fastness and PVC migrationresistance) and penetration.

APPLICATION EXAMPLE C

[0113] 100 parts of chrome-tanned bovine upholstery leather are wettedback with 800 parts of water, 2 parts of a 25% ammonia solution and 3parts of the adduct of 10 moles of ethylene oxide to 1 mol ofnonylphenol at 50° C. during 90 minutes. The bath is then drained offand the leather is treated for 15 minutes with 400 parts of water at 40°C., 1.5 parts of a 25% ammonia solution, 2 parts of a fat-liquoringagent (an emulsion of fatty acid esters) and 1 part of a phenolic syntan(condensation product of phenol and sulphuric acid). 6 parts of themetal complex dye obtained in Example 1, previously dissolved in 600parts of water of 50° C., are added and drumming is continued for 60minutes. The bath is then acidified with two subsequent additions of 1.5parts of an 85% formic acid solution, at an interval of 10 minutes.After 10 minutes the leather is rinsed, drained, dried and cured asconventional. There is obtained a leather dyed in an intense levelbordeaux shade with outstanding fastnesses (in particular wetfastnesses, fastness to dry cleaning, fastness to acids, light fastnessand PVC migration resistance).

APPLICATION EXAMPLE D

[0114] 100 parts of chrome tanned bovine upholstery leather is wettedback with 800 parts of water, 2 parts of a 25% ammonia solution and 3parts of the adduct of 10 moles of ethylene oxide to 1 mol ofnonylphenol at 50° C. during 90 minutes. The liquor is then drained offand the leather is treated for 15 minutes with 400 parts of water at 40°C., 1.5 parts of a 25% ammonia solution, 2 parts of a fat-liquoringagent (an emulsion of fatty acid esters) and 1 part of a phenolic syntan(condensation product of phenol and sulphuric acid). The leather is thenpre-dyed with 4 parts of the metal complex dye obtained in Example 1,previously dissolved in 400 parts of water of 50° C. After 60 minutes,the bath is acidified with 1 part of an 85% formic acid solution and,after 10 minutes, 2 parts of a 20% solution of the product obtained byquatemization with dimethylsulphate of the benzylation product ofdiethylenetriamine are added. The bath is drained off after 20 minutesand the leather is dyed at 50° C. with 400 parts of water and 2 parts ofthe same dyestuff as used before for pre-dyeing, previously dissolved in200 parts of water of 50° C., for 40 minutes. The bath is then acidifiedwith 1 part of an 85% formic acid solution and, after 20 minutes, theleather is rinsed, drained, dried and cured as conventional. There isobtained a leather dyed in an intense level bordeaux shade withoutstanding fastnesses (in particular wet fastnesses, fastness to drycleaning, fastness to acids, light fastness and PVC migrationresistance) and full penetration.

APPLICATION EXAMPLE E

[0115] 100 parts of low affinity chrome/vegetable tanned bovine leatheris wetted back at 50° C. with 1000 parts of water and 0.2 parts of theadduct of 10 moles of ethylene oxide to 1 mole of nonylphenol during 90minutes. The bath is then drained off and the leather is dyed at 50° C.with 1000 parts of water and 4 parts of the metal complex dye obtainedin Example 1, previously dissolved in 400 parts of water of 50° C. After1 hour, the bath is acidified with 2 parts of an 85% formic acidsolution, and, after 20 minutes, the leather is rinsed, drained, driedand cured as conventional. There is obtained a leather dyed in a levelbordeaux shade with outstanding fastnesses (in particular wetfastnesses, fastness to dry cleaning, fastness to acids, light fastnessand PVC migration resistance).

APPLICATION EXAMPLE F

[0116] 100 parts of semichrome sheep leather are wetted back at 45° C.with 1000 parts of water and 0.5 parts of an amphoteric masking agent (asulpho group containing fatty acid aminoamide) for 1 hour. The leatheris pre-dyed with 800 parts of water of 50° C. and 6 parts of the metalcomplex dye obtained in Example 1, previously dissolved in 600 parts ofwater of 50° C. Drumming is continued until the dye has penetratedinside the leather. The bath is then acidified with 1.5 parts of an 85%formic acid solution and, after 20 minutes, 2 parts of a 20% solution ofthe product obtained by quaternization with dimethylsulphate of thebenzylation product of diethylenetriamine are added. After 20 minutesthe leather is dyed with 6 parts of the same dye as used for pre-dyeing,previously dissolved in 600 parts of water of 50° C., for 40 minutes.The bath is then acidified with 2 parts of an 85% formic acid solutionand after 30 minutes the leather is rinsed, drained, dried and cured asconventional. There is obtained a leather dyed in a level deep bordeauxshade with outstanding fastnesses (in particular wet fastnesses,fastness to dry cleaning, fastness to acids, light fastness and PVCmigration resistance) and full penetration.

APPLICATION EXAMPLE G

[0117] 100 parts of chrome tanned crust bovine leather for upholsteryare wetted back at 35° C. with 300 parts of water and 0.5 parts of anamphoteric masking agent (a sulpho group containing fatty acidaminoamide) for 20 minutes. The bath is drained off an the leather isretanned at 35° C. with 150 parts of water, 1 part of a phenolic syntan(65% solution of the condensation product of phenol and sulphuric acid)and 3 parts of a 40% solution of dimethyloldihydroxyethylene urea. After30 minutes 1.5 parts of sodium formate are added and, after 15 minutes 5parts of a polypeptide-based retanning agent are added. Drumming iscontinued for 30 minutes and then the pH of the bath is set to 6 byaddition of 1.5 parts of sodium bicarbonate. After 30 minutes theleather is washed for 10 minutes with 300 parts of water at 40° C. Then150 parts of water at 45° C., 1 part of a fat-liquoring agent (anemulsion of fatty acid esters), 1 part of a 25% ammonia solution and 0.5parts of a phenolic syntan (condensation product of phenol and sulphuricacid) are added. After 15 minutes the leather is dyed with 3 parts ofthe metal complex dye obtained in Example 1, previously dissolved in 300parts of water of 50° C., during 90 minutes, i.e. until the dye hasfully penetrated. 2 parts of an emulsion of fatty acid esters, 3 partsof a mixture of an esterified synthetic fatty alcohol and a phosphoricacid partial ester of an ethoxylated fatty alcohol and 6 parts of anemulsion of a sulphited fish-oil are added for fat-liquoring and, after60 minutes, 2 parts of a hydrosoluble melamine-formaldehyde condensateare added for fixation. Drumming is continued for 20 minutes and thenthe bath is acidified with two additions of 0.75 parts of an 85% formicacid solution diluted with water 1:20 v/v, with an interval of 10minutes between the two additions. After 10 minutes the leather isrinsed, drained, dried and cured as conventional. There is obtained aleather dyed in a level bordeaux shade with outstanding fastnesses (inparticular wet fastnesses, fastness to dry cleaning, fastness to acids,light fastness and PVC migration resistance).

APPLICATION EXAMPLE H

[0118] 100 parts of sheep nappa are washed 40° C. with 200 parts ofwater and 0.5 parts of an amphoteric masking agent (a sulpho groupcontaining fatty acid aminoamide) for 20 minutes. The bath is drainedoff, 200 parts of water at 35° C. and 1.2 parts of sodium formate areadded and drumming is continued for 15 minutes. 4 parts of apolypeptide-based retanning agent are then added and after 30 minutes0.6 parts of sodium carbonate are added to adjust the pH of the bath to5.8-6.0. After 40 minutes 4 parts of polyacrylic-acid-based retanningagent are added and drumming is continued for 30 minutes; 2 parts of awater-soluble urea/formaldehyde condensate are then added and after 30minutes the bath is drained off. Then 150 parts of water at 40° C., 1part of a 25% ammonia solution and 2 parts of a fat-liquoring agent (anemulsion of fatty acid esters) are added. After 10 minutes the leatheris dyed with 3 parts of the metal complex dye obtained in Example 1,previously dissolved in 300 parts of water of 50° C., during 90 minutes.2 parts of an emulsion of fatty acid esters, 6 parts of an emulsion of asulphited fish-oil and 3 parts of an aqueous emulsion of fatty alcoholphosphoric acid partial esters are added for fat-liquoring. Drumming iscontinued for 60 minutes and then the bath is acidified with 1.5 partsof an 85% formic acid solution. After 30 minutes the bath is drained offand the leather is rinsed, drained, dried and cured as conventional.There is obtained a leather dyed in a level bordeaux shade withoutstanding fastnesses (in particular wet fastnesses, fastness to drycleaning, fastness to acids, light fastness and PVC migrationresistance).

APPLICATION EXAMPLE I

[0119] Application Example H is repeated, with the difference that afterfat-liquoring and before the conclusive formic acid addition the bath isdrained off, 200 parts of water at 50° C. and 2 parts of a hydrosolublepolymeric reaction product of epichlorohydrin and dimethylamine areadded, drumming is continued for 30 minutes, thereafter 0.5 parts of2-fatty alkyl imidazoline are added and drumming is continued forfurther 20 minutes. The bath is then drained off and the leather isrinsed, drained, dried and cured as conventional. There is obtained aleather dyed in a level bordeaux shade with outstanding fastnesses (inparticular wet fastnesses, fastness to dry cleaning, fastness to acids,light fastness and PVC migration resistance).

[0120] Analogously as the bordeaux dye according to Example 1, the dyesof each of Examples 2 to 21 are used in each of the above ApplicationExamples A to I, by which there are also obtained dyeings ofcorresponding shades indicated in the table, depths and fastnesses.

1. A 1:2-metal complex dye of the formula

wherein R₁ is H, —NO₂, —SO₃M or —NH(C₁₋₂-alkyl), R₂ is H, substitutedC₁₋₄-alkyl, unsubstituted C₁₋₄-alkyl, —NO₂, or —OH, R₃ is H, substitutedC₁₋₄-alkyl, unsubstituted C₁₋₄alkyl, —NO₂, or —OH, R′₁ is H, —NO₂, —SO₃Mor —NH(C₁₋₂-alkyl), R′₂ is H, substituted C₁₋₄-alkyl, unsubstitutedC₁₋₄-alkyl, —NO₂ or —OH, R′₃ is H, substituted C₁₋₄-alkyl, unsubstitutedC₁₋₄-alkyl, —NO₂, or —OH, Y is —OM or —NR₄R₅, Z is —OM or —NR₄′R₅′, R₄is H, C₁₋₄-alkyl, a substituted aromatic ring or an unsubstitutedaromatic ring, R₄′ is H, C₁₋₄-alkyl, a substituted aromatic ring or anunsubstituted aromatic ring, R₅ is H, C₁₋₄-alkyl, a substituted aromaticring or an unsubstituted aromatic ring, R₅′ is H, C₁₋₄-alkyl, asubstituted aromatic ring or an unsubstituted aromatic ring, n is 0 or1, n′ is 0 or 1, M is hydrogen or a cation, (Kat)⁺ is a counter-ion andMe is a complex-forming metal, with the proviso that if Y and Z signifyboth NH₂, Me is not Cr,
 2. A 1:2 metal complex dye according to claim 1,wherein R₁ is hydrogen or —NO₂, R₁′ is hydrogen or —NO₂, R₂ is hydrogen,R₂′ is hydrogen, R₃ is hydrogen, —OH or —NO₂, R₃′ is hydrogen, —OH or—NO₂, Y is hydrogen, —OM or —NHR₄″, R₄″ is hydrogen, methyl or a radicalof formula

R′″ is hydrogen or —COOM₁ and Z is hydrogen or —NHR₄″, or a mixture oftwo or more thereof.
 3. A 1:2 metal complex dye or mixture according toclaim 2, wherein Y is —OM or —NH₂ and Z is a group —NHR₄″, and if Y is—NH₂, R₄″ in Z is not hydrogen.
 4. Mixed 1:2 metal complexes comprisinga mixture of an asymmetrical 1:2 metal complex of formula (I) accordingto claim 1, with the respective symmetrical 1:2 metal complexes offormulae

wherein R₁, R₂, R₃, R′₁, R′₂, R′₃, Y, Z, R₄, R₄′, R₅, R₅′, n, n′, M,(Kat)⁺ and Me are as defined in claim 1, with the proviso that if Y andZ signify both NH₂, Me is not Cr.
 5. A mixture of 1:2 metal complexes offormula (I) according to claim 1, wherein Me is two or more differentcomplex-forming metals.
 6. A process for the production of a 1:2 metalcomplex according to claim 1, comprising the step of metallizing atleast one 1:2-complex-forming metal compound with at least onemonoazocompound of formula

and at least one monoazo-compound of formula

in which, when n or n′ is 1, the carboxy group may optionally be in saltform.
 7. A process for producing mixed 1:2 metal complexes comprisingthe step of metallizing a mixture of two or more differentmonoazocompounds of formulae (II)

wherein R₁ is H, —NO, —SO₃M or —NH(C₁₋₂-alkyl), R₂ is H, substitutedC₁₋₄-alkyl, unsubstituted C₁₋₄-alkyl, —NO₂, or —OH, R₃ is H, substitutedC₁₋₄-alkyl, unsubstituted C₁₋₄-alkyl, —NO₂ or —OH, R′₁ is H, —NO₂, —SO₄Mor —NH(C₁₋₂-alkyl), R′₂is H, substituted C₁₋₄-alkyl, unsubstitutedC₁₋₄-alkyl, —NO₂, or —OH, R′₃ is H, substituted C₁₋₄-alkyl,unsubstituted C₁₋₄-alkyl, —NO₂, or —OH, Y is —OM or —NR₄R₅, Z is —OM or—NR₄′R₅′, R₄ is H, C₁₋₄-alkyl, a substituted aromatic ring or anunsubstituted aromatic ring, R₄′ is H, C₁₋₄-alkyl, a substitutedaromatic ring or an unsubstituted aromatic ring, R₅ is H, C₁₋₄-alkyl, asubstituted aromatic ring or an unsubstituted aromatic ring, R₅′ is H,C₁₋₄-alkyl, a substituted aromatic ring or an unsubstituted aromaticring, n is 0 or 1, n′ is 0 or 1, M is hydrogen or a cation, and Me is acomplex-forming metal, with the proviso that if Y and Z signify bothNH₂, Me is not Cr, with at least one 1:2-complex-forming metal compound,to thereby form a corresponding mixture of an asymmetrical 1:2 metalcomplex of formula (I) according to claim 1, with the respectivesymmetrical 1:2 metal complexes of formulae (Ia) and of formula (Ib). 8.A process according to claim 7, wherein the respective monoazocompoundsof formulae (II) and (III) are metallized with two or more differentcomplex-forming metals, so that there are formed corresponding mixturesof the 1:2 metal complexes of formula (I) wherein Me is two or moredifferent complex forming metal.
 9. Dye composition comprising at leastone dye of formula (I) according to claim
 1. 10. A method for dyeing asubstrate dyeable with anionic dyes comprising the step of dyeing thesubstrate with at least one 1:2-metal complex dye according to claim 1.11. A method for dyeing leather dyeable with anionic dyes comprising thestep of dyeing the leather with at least one 1:2-metal complex dyeaccording to claim
 1. 12. A substrate dyed by the process according toclaim
 10. 13. A mixture of 1:2-metal complex dyes comprising at leasttwo 1:2-metal complex dyes according to claim
 1. 14. Leather dyed by theprocess according to claim 11.